Expandable intervertebral implant and associated method of manufacturing the same

ABSTRACT

An expandable intervertebral implant ( 10 ) includes superior ( 20 ) and inferior ( 30 ) bone contacting members and at least one vertical wire netting ( 50 ) interconnecting the superior and inferior bone contacting members. The superior and inferior bone contacting members include at least two bone contacting components interconnected via one or more lateral wire nettings such that the implant is vertically and laterally expandable in situ from a first insertion configuration to a second expanded configuration. The vertical and lateral wire netting are preferably constructed of a plurality of individual link members. The present invention also preferably relates to an associated method of manufacturing the intervertebral implant such that the intervertebral implant can be manufactured as an integral component or part.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/021,778, filed on Jan. 17, 2008, entitled “INTERVERTEBRAL SPACEAUGMENTATION,” the contents of which is incorporated in its entirety byreference herein.

BACKGROUND OF THE INVENTION

People, especially elderly people, may suffer from osteoporosis. Oneaspect of osteoporosis may be the partial or complete collapse of thebony structure of the spine, which in turn can cause loss of vertebralheight, fracture of a vertebral disc, facet and nerve impingement, etc.Collapse of the spine often results in, for example, pain, reduction oflung function, unbalanced stature, etc. One treatment option may be asurgical procedure to re-align the vertebra (e.g., to re-establishbalanced curvature of the spine as well as the intervertebral discspace).

Re-alignment of a spine including a damaged vertebra or disc may beaccomplished by replacing the damaged vertebra, disc or portions thereofwith an intervertebral implant. That is, an intervertebral implant maybe inserted into the intervertebral disc space of two neighboringvertebral bodies or into the space created by removal of portions of orthe entire vertebral body after removal of damaged portions of thespine. Preferably, the intervertebral implant restores the spine, asmuch as possible, to a natural state, i.e. to restore the originalheight of the intervertebral disc or the series of vertebra and, thus,the original distance between the two neighboring or adjacent vertebralbodies or vertebral bodies in various levels of the spine.

Typically implantation of one or more intervertebral implants is notpart of a treatment procedure for osteoporosis. One reason for this maybe that intervertebral implants are often designed with high structuralstiffness. Osteoporotic bone is usually brittle, thus increasing therisk of breaking a vertebral endplate during a surgery or implantationof an implant and the endplates may have a uneven surface. For example,a stiff implant may impact a point or small area of an uneven surface ofthe osteoporotic bone, thereby creating a stress concentration andpotentially damaging the bone. Therefore, the incorporation of anintervertebral implant in certain cases, is contra-indicated forpatients with osteoporotic bone. Another reason for not incorporating anintervertebral implant may be that the insertion approach for implantingan intervertebral implant is difficult and risky, especially in elderlypatients.

Alternatively, rather than implanting an intervertebral implant, asurgeon may elect to perform a Vertebralplasty and/or Cavitoplastyprocedure on the patient's spine. In an exemplary method of performing aVertebralplasty and/or Cavitoplasty procedure, a protective sleeve orcannula may be inserted into the patient's body, adjacent to thepatient's spine. The spine may then be re-aligned if fractured orre-fractured. Next cement is inserted into the spine to replace lostbone and/or to limit future cracks. After the hardening of the cement,the treated section of the spine may be re-aligned and the patient maythen return to his or her daily activity. In a Cavitoplasty procedure, acavity may be formed in one or more of the vertebral bodies forreceiving a portion of the cement.

It would be desirable to construct an intervertebral implant that isrelatively simple to insert into a patient's spine at a relatively smallsize and which is able to expand to restore the original height of theremoved spinal material or to a height desired by a surgeon. It wouldalso be desirable to construct an intervertebral implant that isadaptable to uneven surfaces of an osteoporotic vertebral bone to limitstress concentrations when the implant is expanded and contacts orapplies pressure to a patient's endplate.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to an expandable intervertebral implant.More particularly, a preferred embodiment of the present inventionrelates to an intervertebral implant that is laterally and verticallyexpandable in situ from a collapsed, non-expanded or first insertionconfiguration to a second expanded configuration. The expandableintervertebral implant preferably includes superior and inferior bonecontacting members connected together via one or more expandablecomponents such as, for example, a wire netting so that the implant isvertically expandable in the cranio/caudal direction. The superior andinferior bone contacting members preferably are formed by two or morebone contacting components connected together via one or more expandablecomponents such as, for example, a wire netting so that the implant islaterally expandable in the lateral direction if implanted via ananterior approach or laterally expandable in the anterior-posteriordirection if implanted via a lateral approach.

The present invention also relates to an associated method of insertingand sequentially expanding the intervertebral implant and an associatedmethod of manufacturing the intervertebral implant such that theintervertebral implant can be manufactured as an integral component.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofthe preferred embodiments of the application, will be better understoodwhen read in conjunction with the appended drawings. For the purposes ofillustrating the expandable intervertebral implant, surgical method forimplanting the intervertebral implant and manufacturing method forforming the intervertebral implant of the present application, there areshown in the drawings preferred embodiments. It should be understood,however, that the application is not limited to the precise arrangementsand instrumentalities shown. In the drawings:

FIG. 1 illustrates a top perspective view of an exemplary intervertebralimplant according to the present invention, the implant illustrated inthe collapsed, non-expanded or first insertion configuration;

FIG. 2 illustrates a top perspective view of the intervertebral implantshown in FIG. 1, the implant illustrated in a second, expandedconfiguration;

FIG. 3A illustrates a side elevational view of the intervertebralimplant shown in FIG. 1, the implant illustrated in the collapsed,non-expanded or first insertion configuration;

FIG. 3B illustrates a side elevational view of the intervertebralimplant shown in FIG. 1, the implant illustrated in the second expandedconfiguration;

FIG. 4A illustrates a top plan view of the intervertebral implant shownin FIG. 1, the implant illustrated in the collapsed, non-expanded orfirst insertion configuration;

FIG. 4B illustrates a top plan view of the intervertebral implant shownin FIG. 1, the implant illustrated in the second expanded configuration;

FIG. 5A illustrates a front elevational view of the intervertebralimplant shown in FIG. 1, the implant illustrated in the collapsed,non-expanded or first insertion configuration;

FIG. 5B illustrates a front elevational view of the intervertebralimplant shown in FIG. 1, the implant illustrated in the second expandedconfiguration;

FIG. 6A illustrates a top perspective view of a first preferredembodiment of a link member that may be used to form wire netting thatmay be used in conjunction with the intervertebral implant shown in FIG.1;

FIG. 6B illustrates a top plan view of the wire netting shown in FIG.6A, the wire netting illustrated in an at least partially collapsed,non-expanded or first insertion configuration;

FIG. 6C illustrates a top plan view of the wire netting shown in FIG.6A, the wire netting illustrated in the second expanded configuration;

FIG. 7 illustrates a top perspective view of a second preferredembodiment of a link member that may be used to form wire netting thatmay be used in conjunction with the intervertebral implant shown in FIG.1;

FIG. 8 illustrates a top perspective view of a third preferredembodiment of a link member that may be used to form wire netting thatmay be used in conjunction with the intervertebral implant shown in FIG.1;

FIG. 9 illustrates a top perspective view of a fourth preferredembodiment of a link member that may be used to form wire netting thatmay be used in conjunction with the intervertebral implant shown in FIG.1;

FIGS. 10A-10C illustrate various cross-sectional views of theintervertebral implant shown in FIG. 1, the superior and inferior bonecontacting members incorporating wire netting so that the superior andinferior bone contacting members are able to adapt and/or conform to theendplates of the superior and inferior vertebral bodies V, respectively;

FIGS. 11A-11E illustrate various perspective views of steps of anexemplary surgical method for laterally inserting the expandableintervertebral implant of FIG. 1 in accordance with one aspect of thepreferred invention; and

FIGS. 12A-12L illustrate various top, perspective views of steps of anexemplary method for manufacturing the expandable intervertebral implantof FIG. 1 in accordance with one aspect of the preferred invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “right”, “left”, “top” and “bottom”designate directions in the drawings to which reference is made. Thewords “inwardly” and “outwardly” refer to directions toward and awayfrom, respectively, the geometric center of the device and designatedparts thereof. The words, “anterior”, “posterior”, “superior”,“inferior”, “lateral” and related words and/or phrases designatepreferred positions and orientations in the human body to whichreference is made and are not meant to be limiting. The terminologyincludes the above-listed words, derivatives thereof and words ofsimilar import.

Certain exemplary embodiments of the invention will now be describedwith reference to the drawings. In general preferred embodiments of thepresent invention are directed to (i) an expandable intervertebralimplant 10 for implantation between or to replace damaged portions ofadjacent vertebral bodies V in a patient's spine (for example, in thelumbar, thoracic or cervical regions), (ii) an exemplary surgical methodfor implanting the intervertebral implant 10 between adjacent vertebralbodies V in the patient's spine and (iii) an exemplary method ofmanufacturing the intervertebral implant 10. More specifically, thepresent invention is preferably directed to an expandable intervertebralimplant 10 for total or partial disc or vertebral body V replacement orfor nucleus replacement of an intervertebral disc space S. It should beappreciated that while the expandable intervertebral implant 10 of thepresent application will be described in connection with spinal discreplacement, one of ordinary skill in the art will understand that theimplant 10 as well as the components thereof may be used for replacementof tissue in other parts of the body including, for example, knee, hip,shoulder, finger or other joint replacement or for bone augmentation.

Referring to FIGS. 1-5B, as will be described in greater detail below,the expandable intervertebral implant 10 is preferably used forintervertebral support of the spine for patients that require interbodyfusion at one or more levels of the spine. The expandable intervertebralimplant 10 is preferably implanted by a surgeon into the patient's bodyin a collapsed, non-expanded or first insertion configuration (as bestshown in FIGS. 1, 3A, 4A and 5A), thereby allowing a smaller incisionthan is typically necessary for implantation of a non-expandableintervertebral implant (not shown). Implantation of the preferredexpandable intervertebral implant 10 in the first insertionconfiguration may also make it easier to insert the implant 10 paststructures that may inhibit a surgeon's access to the spine. Theexpandable intervertebral implant 10 allows surgeons to implant a largerintervertebral implant in the disc space S, generally without having todo an excessive amount of boney resection and soft tissue retraction.Once the implant 10 is inserted into the disc space S, the implant 10may be expanded to a second expanded configuration (as best shown inFIGS. 2, 3B, 4B and 5B). More preferably, the implant 10 is expandablein the cranio/caudal direction to provide parallel and/or lordoticintervertebral distraction and in the lateral direction. That is, theexpandable intervertebral implant 10 is preferably implanted by asurgeon into the patient's body in a collapsed, non-expanded or firstinsertion configuration wherein the implant has a first height H₁ and afirst width W₁. Thereafter, once inserted into the disc space S, theimplant 10 may be expanded to a second expanded configuration whereinthe implant 10 has a second height H₂ and a second width W₂, wherein thesecond height H₂ and the second width W₂ are larger than the firstheight H₁ and the first width W₁, respectively.

The preferred expandable intervertebral implant 10 may, for example,fill the entire intervertebral disc space S to replace the entireintervertebral disc. Alternatively, a plurality of expandableintervertebral implants 10 may be used to fill the intervertebral discspace S. For example, two or more smaller expandable intervertebralimplants 10 may be used to fill the intervertebral disc space S.Alternatively, the expandable intervertebral implant 10 may be sized andconfigured to only partially replace an intervertebral disc space S,such as for example, to replace a nucleus. In addition, the preferredintervertebral implant 10 may be configured to replace a disc and aportion of a damages vertebra V.

The expandable intervertebral implant 10 preferably includes a superiorbone contacting member 20 for contacting a first, superior vertebra V,an inferior bone contacting member 30 for contacting a second, inferiorvertebra V and a vertical wire netting or mesh 50 for interconnectingthe superior and inferior bone contacting members 20, 30 with respect toone another. The vertical wire netting 50 preferably enables thesuperior and inferior bone contacting members 20, 30 to move (e.g.,expand) in the cranial/caudal direction or generally away from eachother during movement from the collapsed, non-expanded or firstinsertion configuration to the second expanded configuration when theimplant 10 is inserted into the disc space S. The superior and inferiorbone contacting members 20, 30 are sized and configured to contact atleast a portion of the endplates of the superior and inferior vertebralbodies V, respectively, or to engage a surface of the superior and/orinferior vertebral bodies V remaining after damaged portions of thesuperior and/or inferior vertebrae V are removed from the spine. Thesuperior and inferior bone contacting members 20, 30 preferably define acavity 40 therebetween.

The superior bone contacting member 20 of the exemplary preferredembodiment is formed by two or more bone contacting components 22interconnected by a lateral wire netting or mesh 50′. Similarly, theinferior bone contacting member 30 of the exemplary preferred embodimentis formed by two or more bone contacting components 32 interconnected bythe lateral wire netting 50′. That is, the superior and inferior bonecontacting members 20, 30 are each preferably constructed by a pluralityof generally rigid bone contacting components 22, 32 separated by orinterconnected by the lateral expandable wire netting 50′ so that thebone contacting components 22, 32, which form the bone contactingmembers 20, 30, are moveable (e.g., expandable) with respect to oneanother. As shown, the bone contacting components 22, 32 preferably arein the form of one or more plates, more preferably an L-shaped plate,although other shapes are contemplated. However, the bone contactingmembers 20, 30 may be constructed as a single integral component, forexample, if the implant 10 is constructed to expand only in thecranial/caudal direction. In addition, the superior and inferior bonecontacting members 20, 30 may have convex-shaped surfaces wherein theycontact the endplates of the vertebra V to conform to the shape of theendplates.

In this manner, by incorporating the vertical wire netting 50 betweenthe superior and inferior bone contacting members 20, 30, the implant 10is expandable from the collapsed, non-expanded or first insertionconfiguration wherein the implant 10 has a first height H₁ to the secondexpanded configuration wherein the implant 10 has a second height H₂,wherein the second height H₂ is larger than the first height H₁.Similarly, by incorporating the lateral wire netting 50′ between theadjacent bone contacting components 22, 32, which form the superior andinferior bone contacting members 20, 30, respectively, the implant 10 isexpandable from the collapsed, non-expanded or first insertionconfiguration wherein the implant 10 has a first width W_(i) to a secondexpanded configuration wherein the implant 10 has a second width W₂,wherein the second width W₂ is larger than the first width W₁. That is,the lateral wire netting 50′ preferably enables the bone contactingcomponents 22, 32 to be laterally moveable (e.g., in theanterior-posterior or lateral direction depending on insertionprocedure) with respect to one another along a lateral axis A₂ while thevertical wire netting 50 enables the superior and inferior bonecontacting members 20, 30 to be vertically moveable with respect to oneanother along a vertical axis A₃. In addition, the vertical and lateralwire netting 50, 50′ enables the superior bone contacting member 20 tomove with respect to the inferior bone contacting member 30 along alongitudinal axis A₁. Thus, the vertical and lateral wire netting 50,50′ enables the implant 10 to conform its final shape in the second orexpanded configuration to mate to the typically uneven surfaces of theendplates of the vertebral bodies V. In addition, the vertical andlateral wire netting 50, 50′ enables the implant 10 to limit stressrisers at contact points between the implant 10 and the vertebral bodiesV thus making the preferred implant 10 applicable for insertion betweenosteoporotic bone.

That is, in the preferred embodiment, by forming the preferred implant10 from four bone contacting components 22, 32 interconnected byvertical and lateral wire netting 50, 50′, the superior and inferiorbone contacting members 20, 30 of the implant 10 are preferably able tomove in six degrees of freedom with respect to each other. Specifically,the superior and inferior bone contacting members 20, 30 are able tomove longitudinally relative to each other along the longitudinal axisA₁, laterally relative to each other along the lateral axis A₂,vertically relative to each other along the vertical axis A₃, pivot orroll relative to each other about the longitudinal axis A₁, pivot orpitch relative to each other about the lateral axis A₂ and pivot or yawrelative to each other about the vertical axis A₃. Accordingly, thepreferred implant 10 is able to conform its final shape in the second orexpanded configuration to mate to the typically uneven surfaces of theendplates of the vertebral bodies V and limit stress risers at contactpoints between the implant 10 and the vertebral bodies V.

It should be noted that it is also envisioned that the superior andinferior bone contacting members 20, 30 may be formed of four or morebone contacting components 22, 32 interconnected by lateral wire netting50′ and longitudinal wire netting (not shown) so that the implant 10 islongitudinally moveable from a first length to a second length (notshown). Alternatively, the superior and inferior bone contacting members20, may be formed of two bone contacting components 22, 32interconnected by longitudinal wire netting (not shown) but not lateralwire netting 50′ so that the implant 10 is longitudinally moveable froma first length to a second length (not shown) but not laterally moveablefrom the first width W₁ to the second width W₂.

The vertical wire netting 50 and the lateral wire netting 50′,preferably enable approximately three tenths of a millimeter (0.3 mm) toapproximately twelve millimeters (12 mm) of movement, although otheramounts of movement are permissible as would be apparent to one havingordinary skill in the art. Further, the implant is not limited to havingthe generally rectangular or box-shaped configuration shown in FIGS.1-12L, for example, the implant 10 may have a generally circular orcylindrical-shaped series of rings that form the superior and inferiorbone contacting members 20, 30 separated by wire netting such that aninner ring may expand along the vertical axis A3 further than an outerring to conform to a concave-shaped endplate.

Referring to FIGS. 6A-6C, a first preferred, exemplary embodiment of thevertical and/or lateral wire netting 50, 50′ is formed byinterconnecting a plurality of individual first link members 52. Asshown, the plurality of individual first link members 52 may have agenerally rectangular shape when at least partially expanded but are notso limited. Referring to FIG. 7, a second preferred exemplary embodimentof the lateral and/or vertical wire netting 50, 50′ may be formed byinterconnecting a plurality of individual second link members 52′wherein the plurality of individual second link members 52′ have agenerally trapezoidal shape when at least partially expanded but are notso limited. Referring to FIG. 8, a third preferred, exemplary embodimentof the vertical and/or lateral wire netting 50, 50′ may be formed byinterconnecting a plurality of individual third link members 52″ whereinthe plurality of individual think link members 52″ have an alternate,second rectangular shape when at least partially expanded but are not solimited. Referring to FIG. 9, a fourth preferred, exemplary embodimentof the vertical and/or lateral wire netting 50, 50′ may be formed byinterconnecting a plurality of individual fourth link members 52′″wherein the plurality of individual fourth link members 52′″ have analternate, third rectangular shape when at least partially expanded butare not so limited. Alternatively, the vertical and/or lateral wirenetting 50, 50′ may have any other form or shape such as, for example, aplastically deformable material, mesh, stent, etc. so long as thevertical and/or lateral wire netting 50, 50′ interconnects and enablesthe superior and inferior bone contacting members 20, and/or thesuperior and inferior bone contacting components 22, 32 to move withrespect to one another. The preferred individual link members 52, 52′,52″, 52′″ are not limited to the generally rectangular or trapezoidalshapes and may take nearly any shape such as, for example, oval,circular, triangular, hexagonal, etc.

In addition, by forming or constructing the vertical and/or lateralwire-netting 50, 50′ from a plurality of preferred individual first,second, third and/or fourth link members 52, 52′, 52″, 52′″ the superiorand/or inferior bone contacting components 22, 32 are able to tilt orgenerally move with respect to one another so that the superior andinferior bone contacting members 20, 30 are better able to conform tothe configuration of the endplates of the adjacent vertebral bodies V.That is, as previously described above, by forming the preferred implant10 from four bone contacting components 22, 32 interconnected byvertical and lateral wire netting 50, 50′, the flexible of the verticaland/or lateral wire netting 50, 50′ enables the superior and inferiorbone contacting members 20, 30 of the implant 10 to move in six degreesof freedom with respect to each other so that the implant 10 and moreparticularly the superior and inferior bone contacting members 20, 30are better able to adapt and/or conform to the anatomical shape of theendplates of the superior and inferior vertebral bodies V, respectively.As illustrated in FIGS. 10A-10C, the superior and inferior bonecontacting components 22, 32 are better able to adapt and/or conform tothe endplates of the superior and inferior vertebral bodies V,respectively, due to the inherent flexibility or adaptability of formingthe superior and inferior bone contacting members 20, 30 from multiplecomponents 22, 32 interconnected by a flexible wire netting 50, 50′.Thus, in use, the lateral wire netting 50′ enables the superior bonecontacting components 22 to move with respect to one another and enablesthe inferior bone contacting components 32 to move with respect to oneanother such that the lateral wire netting 50′ enables the superior andinferior bone contacting members 20, 30 to adapt and/or conform to theendplates of the superior and inferior vertebral bodies V, respectively.

The preferred implant 10 also includes a cavity 40 located between thesuperior and inferior bone contacting members 20, 30. The cavity 40 ispreferably sized and configured to receive a filling material (notshown) and/or a balloon 75, an expansion sack, an expansion bag, etc.(collectively referred to herein as an “expansion member”). Theexpansion member 75 is preferably sized and configured to be receivedwithin the cavity 40 in order to limit any filling material fromoverflowing and escaping from the cavity 40. More preferably, as will bedescribed in greater detail below, once the implant 10 has beenimplanted and positioned, the expansion member 75 is preferably insertedinto the cavity 40. Thereafter, the filling material may be insertedinto the expansion member 75, expanding the expansion member 75 so thatthe implant 10 is expanded from the collapsed, non-expanded or firstinsertion configuration to the second expanded configuration. Onceinserted, the filling material preferably hardens or is cross-linked inorder to support the implant 10 in the second expanded configuration.Alternatively, the filling material may not harden and may partiallyharden into a gel-like material or may retain a flowable or liquid stateand become sealed in the expansion member 75.

It should be noted that expanding of the expansion member 75 may or maynot cause distraction of the adjacent vertebral bodies V. However, theflexibility of the expansion member 75 and the sequential hardening ofthe filling material preferably provide a geometrically adaptedrestoration of the intervertebral disc space S. Alternatively, thefilling material may remain in a gel and/or liquid state and may besealed in the expansion member 75. In addition, as will be generallyappreciated by one of ordinary skill in the art, the expansion member 75may be inserted into the cavity 40 prior to implantation of the implant10, the filling material may be injected into the expansion member 75prior to implantation of the implant 10, the expansion member 75 may beintegrated with or coupled to the implant 10, and/or the expansionmember 75 may be omitted entirely.

Moreover, it should be understood that the superior and inferior bonecontacting members 20, 30 may include any number of bone contactingcomponents 22, 32 and interconnecting lateral wire netting 50′ such as,for example, three bone contacting components 22, 32 interconnected bytwo lateral wire nettings 50′. It is also envisioned that the implant 10may include one or more intermediate components (not shown) between thesuperior and inferior bone contacting members 20, 30. The intermediatecomponents may be coupled to the superior and inferior bone contactingmembers 20, 30 via the vertical wire netting 50. Moreover, it is alsoenvisioned that the implant 10 may include the vertical wire netting 50to enable cranio/caudal expansion without incorporating the lateral wirenetting 50′. Alternatively, the implant 10 may include the lateral wirenetting 50′ to enable lateral expansion without incorporating thevertical wire netting 50.

The superior and inferior bone contacting members 20, 30 may includemeans for increasing the stability of the implant 10, such as, forexample, one or more projections, one or more roughened surfaces, one ormore undulating structures, one or more ridges, one or more keels, etc.Preferably, the superior and inferior bone contacting members 20, 30include a plurality of teeth 21 for increasing the stability of theimplant 10.

The implant 10 may also include a mechanism or feature for engaging animplant insertion instrument (not shown). The mechanism or feature forengaging the insertion instrument may take on any form now or hereafterknown including, for example, one or more bores 102 for receiving one ormore projections (not shown) formed on the implant insertion instrument,one or more projections (not shown) for engaging one or more bores (notshown) formed on the implant insertion instrument, one or more channels(not shown) for receiving one or more tips formed on the implantinsertion instrument, one or more threaded bores (not shown) forreceiving one or more threaded shafts or screws, etc.

The implant 10 may also include a mechanism or features for reducingand/or preventing shearing or dismantling of the implant 10 duringinsertion such as, for example, the superior and inferior bonecontacting members 20, 30 may include interconnecting projections 24 andbores 34 for temporarily securing the implant 10 in its collapsed orinsertion configuration.

The superior and inferior bone contacting members 20, 30 may be formedfrom any biocompatible material including, but not limited to, a metal,such as, for example, cobalt-chromium-molybdenum (CCM) alloys, titanium,titanium alloys, stainless steel, aluminum, etc., a ceramic such as, forexample, zirconium oxide, silicone nitride, etc., an allograft, anautograft, a metal-allograft composite, a polymer such as, for example,polyaryl ether ketone (PAEK), polyether ether ketone (PEEK), polyetherketone ketone (PEKK), polyetherketone (PEK), polyetherketoneether-ketone-ketone (PEK-EKK), etc. The polymers may be reinforced witha fiber such as, for example, a carbon fiber or other thin, stiff fiber.

The superior and inferior bone contacting members 20, 30 may also becoated in order to enhance their osteo-conductive properties. Forexample, the bone contacting members 20, 30 may be coated with anetching, anodization, an anodic plasma chemical process, electrolyticdeposition, plasma spraying, a thin layer of titanium (Ti) via aphysical or chemical vapor deposition process, an anodic plasma chemicalsurface treatment incorporating, for example, Ca and/or P in theTi-Oxide surface layer or via a Ti or HA plasma spray, etc.

The expansion member 75 may be manufactured from any biocompatiblematerial including, but not limited to, a polyurethane, a polycarbonateurethane, a poly carbonate-silicone urethane copolymer, polyamine,polyethylene terephthalate (PET), polycaprolactone, etc.

The filling material may be any biocompatible material known in the artand may be a rigid or elastic material. The filling material may becomprised of, for example, a bone cement, a hydrogel, a polyvinylalcohol, a sodium polyacrylate, an acrylate polymer, amethyl-methacrylate, a co-polymer with an abundance of hydrophilicgroups, p-vinyl pyrollidone, polyethyleneimine, etc., a setting orcuring hydrogel based co-polymer such as, for example,polyethyleneimine, poly(diethylaminoethyl methacrylate),poly(ethylaminoethyl methacrylate), etc., a thermally setting hydrogelbased co-polymers, such as, for example, poly-N-isopropylacrylamide withpolyethylene glycol, copolymers of polyethylene oxide andpolyphenelylene oxide, copolymers of polyethylene glycol andpolyactides, etc., an ionic setting hydrogel such as, for example,ethylacrylate, methacrylic acid, 1,4-butanediacrylate, etc., or a PCU,PCU-silicone co-polymer, silicone or other non-resorbable pure orelastic co-polymer (e.g., PCU's silicone end group modified PU's, RTVcuring siloxane based elastomers, etc.).

Exemplary Method of Inserting the Intervertebral Implant

The expandable intervertebral implant 10 may be inserted within thetargeted intervertebral disc space S by any means, method, or approachnow or hereafter known in the art including, but not limited to, viaanterior, lateral, posterior, anterior-lateral, or posterior-lateralapproaches, etc. Preferably, the implant 10 is implanted using aminimally invasive technique. Alternatively, the implant 10 may beimplanted via an open incision, as would be appreciated by one havingordinary skill in the art.

Referring to FIGS. 11A-11E, in one exemplary method of inserting theimplant 10 via a lateral approach, the implant 10 is inserted into theintervertebral disc space S between adjacent superior and inferiorvertebral bodies V via an insertion instrument (not shown). Asillustrated in FIG. 11A, the implant 10 is preferably inserted into theintervertebral disc space S in the collapsed, non-expanded or firstinsertion configuration following a preferably minimal incision throughthe skin to the disc space S. As illustrated in FIG. 11B, the implant 10is preferably positioned within the intervertebral disc space S at leastpartially in a posterior direction in order to generally keep the motionsegment in balance. More preferably, the implant 10 should be positionedso that the implant 10 engages the stronger peripheral aspects of theadjacent vertebral bodies V. Once the implant 10 has been properlypositioned in its desired location, as illustrated in FIG. 11C, theimplant 10 is preferably laterally expanded in the anterior-posteriordirection (in the lateral direction if the implant 10 was inserted viaan anterior or posterior approach) via a surgical instrument (notshown). Alternatively, the implant 10 may be inserted with the expansionmember or balloon 75 therein and laterally expanded via the expansionmember 75. Preferably, the implant's position should be checked at thispoint to ensure preferred positioning. Once the position of the implant10 is verified based generally on surgeon preference and/or physiology,as illustrated in FIG. 11D, the expansion member 75 is inserted andpositioned within the cavity 40 formed in the implant 10 via aninsertion instrument (not shown). The implant 10 may be slightlyexpanded via the implant insertion instrument in order to ease insertionof the expansion member 75 within the cavity 40, if necessary. Next theexpansion member 75 is filled with a filling material, which causes theimplant 10 to expand in the cranio/caudal direction, preferablyresulting in the implant 10 firmly penetrating into the endplates of theadjacent superior and inferior vertebral bodies V. Due to theadaptability of the vertical and/or lateral wire netting 50, 50′, thesuperior and inferior bone contacting members 20, 30 of the implant 10may substantially mate to the typically uneven surfaces of the endplatesof the superior and inferior vertebral bodies V, respectively. Forexample, the individual bone contacting members 22, 32 may move linearlyrelative to each other along the longitudinal, lateral and/or verticalaxes A1, A2, A3 and may pivot relative to each other about thelongitudinal, lateral and/or vertical axes A1, A2, A3 such that theshape of the implant 10 in the expanded configuration conforms to theanatomical shape of the pre-existing endplates of the vertebrae V.Specifically, each of the bone contacting members 22, 32 are movablerelative to each other in six degrees of freedom to permit theindividual components to adapt their final position to the patient'sanatomy, thereby reducing stress risers that may develop when an implantis unable to conform to the shape of the anatomy.

Exemplary Method of Manufacturing the Intervertebral Implant

The preferred expandable intervertebral implant 10 may be manufacturedby any means and/or method now or hereafter known in the art including,but not limited to, by manufacturing each of the bone contacting members20, 30 as separate and distinct components and then coupling each of thecomponents to vertical and lateral wire netting 50, 50′, as required.

Preferably, however, the implant 10 is formed as an integral implantmanufactured via a layer-wise or layer by layer manufacturing process.For example, referring to FIGS. 12A-12L, the implant 10 preferably ismanufactured via a selective laser melting process. The metal componentsare preferably set up in layers, similar to a stereo-lithograph. In use,a thin layer of metal powder is applied to a platform. The powder isthen locally melted by, for example, a laser beam. The platform is thenlowered by a defined layer height. Another thin layer of metal powder isthen applied. The second layer of powder is then locally melted. Thisprocess is repeated until the implant 10 is complete. The ability tomanufacture the implant 10 as a single or integral component or partpermits the manufacture of continuous loops or solid vertical andlateral wire netting 50, 50′ between the bone contacting components 22,32. In contrast, alternate techniques for constructing the vertical andlateral wire netting 50, 50′ may require joining together of ends of thewires to construct the preferred first, second, third and fourth linkmembers 52, 52′, 52″, 52′″.

Alternatively, the implant 10 may be manufactured via a selective lasersintering process. Generally, the laser sintering process follows thesame steps as the selective laser melting process described above.However since sintering is performed below the melting point of thesubstrate material, the laser sintering process allows the originalmetal powder to be mixed with a binding agent. A steam stripping processmay be used after the laser sintering process. Using the laser sinteringprocess, combinations of metals as well as micro-porous structures canbe manufactured. The laser sintering process may also be used inconnection with thermoplastic polymers which do not have any specificmelting point but rather have a transition zone between a glasstransition temperature and a melt mass temperature.

While laser melting and sintering processes have been described, othermanufacturing methods are contemplated including, but not limited to,other methods of curing or sintering such as, for example, the use ofultrasonic or ultraviolet rays.

Features described herein may be used singularly or in combination withother features. In addition, features disclosed in connection with oneembodiment may be interchangeable with a feature or features disclosedin another embodiment. Therefore the presently disclosed embodiments areto be considered as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims, and not limited to theforegoing description.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but isintended to cover modifications within the spirit and scope of thepresent invention as defined by the appended claims.

1. An expandable intervertebral implant comprising: a superior bonecontacting member including at least two bone contacting componentsinterconnected via a first lateral wire netting; an inferior bonecontacting member including at least two bone contacting componentsinterconnected via a second lateral wire netting; and at least onevertical wire netting interconnecting the superior and inferior bonecontacting members, wherein the first lateral wire netting, the secondlateral wire netting and the vertical wire netting comprise a pluralityof individual link members, the implant being expandable in situ from afirst insertion configuration to a second expanded configuration, theimplant having a first height and a first width in the first insertionconfiguration and a second height and a second width in the secondexpanded configuration, the second height being larger than the firstheight and the second width being larger than the first width.
 2. Theimplant of claim 1, wherein the plurality of individual link membershave a rectangular shape.
 3. The implant of claim 1, wherein theplurality of individual link members have a trapezoidal shape.
 4. Theimplant of claim 1, further comprising: a cavity defined between thesuperior bone contacting member and the inferior bone contacting member;and an expansion member insertable in the cavity, the expansion membercapable of receiving a filling material so that injection of the fillingmaterial into the expansion member permits the vertical wire nettinginterconnecting the superior and inferior bone contacting members toexpand, thereby moving the superior bone contacting member with respectto the inferior bone contacting member such that the implant verticallyexpands from the first height to the second height.
 5. The implant ofclaim 4, wherein the at least two bone contacting components that formthe superior and inferior bone contacting members include one or morebores for engaging a surgical instrument.
 6. The implant of claim 1,wherein the at least two bone contacting components that form thesuperior and inferior bone contacting members include interconnectingprojections and bores.
 7. The implant of claim 1, wherein the superiorbone contacting member, the inferior bone contacting member and the atleast one vertical wire netting is constructed as an integral part via alayer-wise manufacturing process.
 8. The implant of claim 7, wherein thelayer-wise manufacturing process is a selective laser melting process.9. The implant of claim 7, wherein the layer-wise manufacturing processis a selective laser sintering process.
 10. A method of manufacturing anexpandable intervertebral implant including superior and inferior bonecontacting members interconnected by at least one wire netting, thesuperior and inferior bone contacting members including at least twobone contacting components interconnected via one or more lateral wirenettings such that the implant is laterally and vertically expandablefrom a first insertion configuration to a second expanded configuration,the at least one wire netting comprising a plurality of individual linkmembers, the method comprising the steps of: (a) applying a first layerof metal powder onto a moveable platform; (b) melting the first layer ofmetal powder to define a first solid layer; (c) lowering the platform bya defined layer height; (d) applying a second layer of metal powder ontothe moveable platform; (e) melting the second layer of metal powder todefine a second solid layer that is interconnected to the first solidlayer; (f) repeating steps (c)-(e) a plurality of times to form theexpandable intervertebral implant having at least two continuousindividual link members.
 11. The method of claim 10, wherein the metalpowder in steps (b) and (e) are melted by a laser beam.